Measuring plant (fruit and vegetable) respiration rates

Plants and indeed most living things get their energy from the chemical reaction of respiration, they use respiration in combination with photosynthesis. Carbon dioxide and water react together in the presence of light and chlorophyll to make glucose and oxygen.

Light levels are extremely important as, in the dark live plants only respire, but in bright light they also photosynthesise. In dim light the balance varies with light level with oxygen is taken in during darkness and emitted under bright light. CO2, however is the complete opposite and is emitted in low light conditions but absorbed in daylight.

Ripening further complicates the diurnal photosynthesis / respiration cycle, as does the fact that once the greenery (basically the chlorophyll) is removed from a picked plant (either fruit or vegetable) it can no longer photosynthesise, but only respire.

All of these have a profound effect on both the shelf life and quality of fruit and vegetables.

Shelf Life and Quality

The shelf life and rate of quality decline in fruits and vegetables is determined by the link between their respiration rates and the vapour permeability of the packaging. This is particularly the case with respect to oxygen, carbon dioxide and water vapour. In the case of modified atmosphere packaging (MAP,) the permeability of the packaging with respect to any gases used, such as nitrogen or argon etc. also becomes critical.

Getting it wrong can actually slash, rather than boost, shelf life.

Our dedicated plant respiration system for fruit and vegetables allows you to measure all of these – both in living and picked produce. It also allows you to control the environmental conditions including temperature, atmosphere and light level. It even allows you to introduce Ethylene (a widely used plant ripening hormone) into the mix.

The equipment provides the ability to measure, with high accuracy, the precise rates of CO2, O2 and water vapour production under these conditions. It can not only measure these in real time for loose fruit and vegetables but it can even measure them when they are actually inside their packaging! – even when they are inside an external chilled cabinet at the time.

The plant respiration meter has a highly automated computerised control and, as well as the instrument we offer both a respiration rate and vapour / gas permeability measurement testing service.